SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0427de9079726ff9ef9b6efac33c41caffb28bf6c0c30c33cd905042e4a8e5' 
  AND token = 'iaXQGM2/akPptBol5sFwzybJ5hUmHogKw4nIk+heK/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}